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US 6,587,115 B2Granted
Method of an apparatus for distinguishing type of pixel
AssigneeRiso Kagaku Corporation
InventorsWeidong Gong, Masato Nakajima
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AssigneeRiso Kagaku Corporation
InventorsWeidong Gong, Masato Nakajima
Estimating the term…
The types of pixels of an image made up of a plurality of pixels arranged in a main scanning direction and a sub-scanning direction are distinguished. The image is divided into a plurality of blocks each substantially larger than a visually distinguishable size, properties of the images in the blocks representing the probability that the image is a binary image are detected, probability that the image in each block is a binary image is determined on the basis of the detected properties of the image in the block, and the blocks are divided into a binary image block, a tone image block, and an indeterminate image block according to the probability that the image is a binary image. The pixels in the blocks which are determined to be a binary image block are all determined to be pixels of a binary image while the pixels in the blocks which are determined to be a tone image block are all determined to be pixels of a tone image. Then a pixel-by-pixel determination is carried out on the blocks, which are determined to be an indeterminate image block by the block-by-block determination, in which properties of each of the pixels in each of the indeterminate blocks representing the probability that the pixel is of a binary image are detected, and whether the pixel is a pixel of a binary image is determined on the basis of the detected properties.
A method of distinguishing the types of pixels of an image made up of a plurality of pixels arranged in a main scanning direction and a sub-scanning direction comprising the steps of;
An apparatus for distinguishing the types of pixels of an image made up of a plurality of pixels arranged in a main scanning direction and a sub-scanning direction comprising
Dependencies are inferred from the claim text.
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Picture signal circuits: discrimination between different image types, e.g. two-tone, continuous tone
Pictorial communication
Term ended 11 Dec 2021 (estimated)
1. Field of the Invention
This invention relates to a method of an apparatus for distinguishing the types of pixels making up an original, and more particularly to a method of and an apparatus for distinguishing the types of pixels making up an original, which are used, for instance, in a stencil printer which makes a stencil by image wise perforating a heat-sensitive stencil material and a print is made from the stencil, and a copier or a printer in which a latent image is formed on a photosensitive medium by electrophotography or the like and a toner image obtained by developing the latent image is transferred to a printing paper or a heat-sensitive paper.
2. Description of the Related Art
FIG. 1 is a block diagram showing an image processing apparatus provided with an apparatus for distinguishing the types of pixels making up an original in accordance with an embodiment of the present invention,
FIG. 2 is a view showing a state in which an original image is divided into a plurality of blocks,
FIGS. 3A to 3D are views showing examples of edge detecting coefficient matrices,
In FIG. 1, an image processing apparatus 1 provided with an apparatus 4 for distinguishing the types of pixels making up an original in accordance with an embodiment of the present invention comprises a block-by-block determination system 2, a pixel-by-pixel determination system 3, a density conversion system 5, a binary-coding system 6 and a line memory 7. The block-by-block determination system 2 and the pixel-by-pixel determination system 3 form the apparatus 4 for distinguishing the types of pixels making up an original in accordance with an embodiment of the present invention.
The block-by-block determination system 2 comprises a block characteristic value calculating section 10, a block type determining section 21, a block type memory 22 and a block type correction section 23. The pixel-by-pixel determination system 3 comprises a pixel characteristic value calculating section 30 and a pixel type determining section 40. The density conversion system 5 comprises a density conversion curve selecting section 51 and a data conversion section 52.
The block characteristic value calculating section 10 comprises a block dividing section 11, an edge pixel ratio calculating section 12, a histogram making section 13, a histogram memory 14, a white pixel ratio calculating section 15, a density center calculating section 16 and a density range calculating section 17.